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2025 Vol.12, Issue 4 Preview Page

Original Article

Analysis on Grain-Size-Dependent Mobility of Gravel Bed Materials in Large-Scale Experimental Flow Conditions

실규모 실험 흐름 조건에서의 자갈 하상 입경별 이동성 분석 연구

Eunkyung Jang1*
,
Woochul Kang2
,
Jaeho Kim3
,
Un Ji45
장 은경1*
,
강 우철2
,
김 재호3
,
지 운45
1Research Specialist, Department of Hydro Science and Engineering Research, Korea Institute of Civil Engineering and Building Technology, Goyang 10223, Korea
2Professor, Department of smart infrastructure engineering, Kongju National University, Goyang 10223, Korea
3Intern, Department of Hydro Science and Engineering Research, Korea Institute of Civil Engineering and Building Technology, Goyang 10223, Korea
4Research Fellow, Department of Hydro Science and Engineering Research, Korea Institute of Civil Engineering and Building Technology, Cheonan 31080, Korea
5Professor, Civil and Environmental Engineering, University of Science & Technology, Goyang 10223, Korea
1한국건설기술연구원 수자원하천연구본부 전임연구원
2국립공주대학교 스마트인프라공학과 교수
3한국건설기술연구원 수자원하천연구본부 인턴
4한국건설기술연구원 수자원하천연구본부 연구위원
5과학기술연합대학원대학교 건설환경공학과 교수
*Corresponding Author
31 December 2025. pp. 291-299
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Abstract

This study is an experimental investigation to determine the grain-size dependent mobility of gravel-bed materials under full-scale flow conditions. Experiments were conducted at the full-scale flume of the Korea Institute of Civil Engineering and Building Technology's Andong River Experiment Center under two hydraulic conditions (Case 1: gate 50% open, discharge 2.683 m3/s, water depth 0.753 m, energy slope 0.00284; Case 2: gate fully open, discharge 2.723 m3/s, water depth 0.752 m, energy slope 0.00286). Gravel particles ranging from 2 to 15 mm were arranged in a specific section to analyze the variation of dimensionless shear stress (τ*) with grain size. The experimental results showed that dimensionless shear stress decreased nonlinearly with increasing grain size, and critical values (τc*) marking the transition between motion and non-motion were identified in the 8-10 mm range for Case 1 and in the 12-15 mm range for Case 2. The calculated critical values were approximately three times higher than the conventional Shields criterion (0.04-0.05), which is interpreted as a combined result of turbulence scale expansion, inter-particle interlocking, and high Reynolds number conditions acting in combination. The results of this study provide experimental evidence for full-scale calibration of the Shields diagram and can be utilized as fundamental data for improving the accuracy of bed stability assessment and sediment transport prediction models in gravel-bed rivers.

Keywords
Critical shear stress
Gravel bed
Large-scale flume experiment
Sediment mobility
Shields parameter

본 연구는 실규모 실험 흐름 조건에서 자갈하상 재료의 입경별 이동성을 규명하기 위한 실험적 연구이다. 한국건설기술연구원 안동하천실험센터의 실규모 수로에서 두 가지 수리 조건(Case 1: 게이트 50% 개방, 유량 2.683 m3/s, 수심 0.753 m, 에너지 경사 0.00284; Case 2: 게이트 완전 개방, 유량 2.723 m3/s, 수심 0.752 m, 에너지 경사 0.00286)에서 실험을 수행하였으며, 2~15 mm 범위의 자갈을 일정 구간에 배열하여 입경에 따른 무차원 전단응력(τ*)의 변화를 분석하였다. 실험 결과, 무차원 전단응력은 입경 증가에 따라 비선형적으로 감소하였으며, Case 1은 8~10 mm, Case 2는 12~15 mm 조건에서 이동과 비이동이 전이되는 한계값(τc*)이 확인되었다. 기존 Shields 도표의 기준값(0.04~0.05)보다 약 3배 높은 한계값이 산정되었으며 이는 난류 스케일 확장, 입자 간 결속, 높은 Reynolds 수 등이 복합적으로 작용한 결과로 해석된다. 본 연구 결과는 Shields 곡선의 실규모 보정에 대한 실험적 근거를 제공하며, 자갈하천의 하상 안정성 평가 및 유사이송 예측 모델의 정확도 향상에 기초자료로 활용될 수 있다.

키워드
한계 전단응력
자갈하상
실규모 수로실험
유사 이동성
Shields 매개변수
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Information
  • Publisher :Korean Society of Ecology and Infrastructure Engineering
  • Publisher(Ko) :응용생태공학회
  • Journal Title :Ecology and Resilient Infrastructure
  • Journal Title(Ko) :응용생태공학회 논문집
  • Volume : 12
  • No :4
  • Pages :291-299
  • Received Date : 2025-11-17
  • Revised Date : 2025-11-24
  • Accepted Date : 2025-11-24
  • DOI :https://doi.org/10.17820/eri.2025.12.4.291
Journal Informaiton Ecology and Resilient Infrastructure Ecology and Resilient Infrastructure
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